272 EARTHQUAKES. 



In the Sandwich Islands Mauna Loa seems to have its 

 eruptions independently of the disturbances which shake 

 these islands.^ 



Synchronism of earthquakes and volcanic erup- 

 tions. — Although many examples like the above may be 

 quoted, which apparently show an utter want of connection 

 between earthquakes and volcanoes, we must not over- 

 look that class of earthquakes which almost invariably 

 accompany all great volcanic disturbances. In fact the 

 sudden explosions which take place at volcanic foci, as, for 

 instance, at the commencement of an eruption, are enume- 

 rated as one of the causes which produce earthquakes. 

 Earthquakes like these usually continue until the pressureof 

 the steam and lava have found for themselves an opening. 

 As compared with the total number of earthquakes which 

 are recorded, they form but an insignificant portion. 



The direct connection which exists between these 

 phenomena has, no doubt, done very much to spread 

 the popular belief that all earthquakes may be connected 

 with volcanic eruptions. As examples where this connec- 

 tion has existed we might quote from almost all the 

 volcanic countries in the world. 



Thus, Fuchs tells us that on October 6, 1737, almost 

 the whole of Kamschatka and the Kurile Islands were 

 disturbed by movements which were simultaneous with 

 the outbreak of the great volcano Klutschenskja of North 

 Kamschatka. 



One of the earliest records of a severe earthquake and 

 a volcanic eruption occurring simultaneously is found 

 in the accounts of the destruction of Herculaneum aiid 

 Pompeii. The throwing up of Monte Nuovo in the neigh- 

 bourhood of Pozzuoli was accompanied with a dreadful 

 earthquake.^ 



^ Notes on volcanoes of the Hawaiitm Islands, W. T. Brigham^ Mem. 

 Boston Soc. of Nat. Hist., 1868. * Gent. Mag. vol. xxiii., 1753. 



